SUBROUTINE EZFFTB (N,R,AZERO,A,B,WSAVE) DIMENSION R(1) ,A(1) ,B(1) ,WSAVE(1) IF (N-2) 101,102,103 101 R(1) = AZERO RETURN 102 R(1) = AZERO+A(1) R(2) = AZERO-A(1) RETURN 103 NS2 = (N-1)/2 DO 104 I=1,NS2 R(2*I) = .5*A(I) R(2*I+1) = -.5*B(I) 104 CONTINUE R(1) = AZERO IF (MOD(N,2) .EQ. 0) R(N) = A(NS2+1) CALL RFFTB (N,R,WSAVE(N+1)) RETURN END